Biomedical subjects

P Schachern

Publications and source records attributed to P Schachern.

12 recordsLinked to original sources

PubMed1996

Residual mesenchyme in temporal bones of children.

The role of mesenchyme in the temporal bone is still poorly understood. A microscopic study of residual mesenchyme was undertaken in temporal bones of children from birth to 5 years of age. Residual mesenchyme was found to be located in the mastoid antrum and epitympanum more often than in the mesotympanum. The amount of mesenchymal tissue remaining in the temporal bones decreased with increasing age. Persistence of mesenchyme in the temporal bone was related to congenital morphologic ear anomalies and syndromes. There was also an association evident with pulmonary disease, but not with congenital heart defects. Persistent mesenchyme was also found to be significantly associated with chronic middle ear inflammation, and in cases of unilateral otitis media the ear with otitis media had more residual mesenchyme than the non-otitis media ear.

Age Factors↗

PubMed1995

Tympanic membrane and otitis media.

The tympanic membrane participates in several ways in the middle ear defense system. It may act as a baroreceptor, contains an important neural network with neurogenic inflammatory mediators, and is particularly rich in mast cells. Histological changes of the tympanic membrane in purulent, serous and chronic otitis media are discussed.

Humans↗

PubMed1994

New developments in treating otitis media.

Treatment of otitis media has changed over time as the disease has become better understood and as clinical experience and technology have expanded and grown. Successful treatment depends on accurate definitions and classifications of types of otitis media. An awareness of the pathogenic and pathologic correlates of otitis media enhances accurate diagnosis and improves the results of treatment. An understanding of the otitis media continuum also assists in management. On the basis of studies largely emanating from the University of Minnesota's Otitis Media Pathogenesis Research Program, we here highlight definitions, classifications, and diagnosis of the otitis medias, and medical treatments of these various clinical and pathologic entities and their sequelae.

Adrenal Cortex Hormones↗

PubMed1993

Potter's syndrome: a temporal bone histopathological study.

Histopathological findings in seven temporal bones from four infants diagnosed as Potter's syndrome are described. The infants were labelled as Potter's syndrome after autopsy confirmed bilateral renal agenesis. Extrarenal manifestations included pulmonary hypoplasia and facial anomalies. The middle ear volume in infants with Potter's syndrome remained unchanged with age resulting in a significantly higher percentage of residual middle ear mesenchyme in these infants as compared to normal infants. Dehiscence of the facial nerve was seen in all the temporal bones studied. One ear showed the presence of eosinophilic effusion in the endolymphatic sac, an underdeveloped malleus and a wide facial nerve canal. The inner ear structures showed no significant anomalies except for the absence of the organ of Corti in the basal turn of the cochlea in one of the ears.

Abnormalities, Multiple↗

PubMed1992

Paediatric otoscopy--clinical and histological correlation.

Otoscopy is a subjective clinical method. Its subjectively has led physicians to verify its accuracy through correlations with findings of otomicroscopy, pneumatic otoscopy, tympanometry, and myringotomy. In the very young population, however, the interpretation of otoscopic findings become more difficult. To improve the interpretation of normal otoscopy in young children, an otoscopic-histological correlation was attempted in children up to nine years of age. Twenty-one temporal bones from 15 children aged from two days to nine years who had no evidence of otological disease or congenital anomalies were examined under light microscopy; the thickness of the pars flaccida, posterior superior quadrant, and umbo were measured. Twenty-five eardrums of 15 healthy children without past or present history of otological disease were examined using otoscopy; a photograph of each eardrum was obtained. Our study demonstrates that structural changes in the tympanic membrane during these years of childhood have a good correlation with otoscopic findings. Understanding normal histological changes in the paediatric eardrum may improve our interpretation of otoscopic findings.

Aging↗

PubMed1991

Pathology of labyrinthine ossification.

Ossification of the inner ear is the result of multifactorial pathogeneses, such as infection or malignant infiltration, and otosclerosis. Ossification of the inner ear spaces is a well documented sequela of suppurative labyrinthitis. In this study of human temporal bones, sections from 14 patients (28 temporal bones) were studied. In addition to the osseous tissue within the inner ear, findings included neoplasms, otosclerosis, otitis media, trauma, and Fabry's disease. We have attempted to correlate these conditions and their influence on the formation of osseous tissue within the spaces of the inner ear. Tympanogenic infection and vascular compromise were found to play an important role in ossification. The scala tympani of the basal turn of the cochlea was frequently the site involved.

Adult↗

PubMed1991

A histopathological study of the relationship between otitis media and mastoiditis.

From a total of 1408 human temporal bones, 229 with otitis media or mastoiditis were selected; other contributing diseases were excluded. Of this group, 19.2% had an obstruction of the aditus ad antrum with pathologic tissue, usually granulation tissue. Although pathologic fluid and tissue were usually distributed throughout the middle ear and mastoid, in some cases, the most severe conditions were restricted to the mastoid. Pathologic conditions were more severe in cases with obstruction. An interesting observation was that columnar epithelial cells, goblet cells, and mucoid effusion were not observed in the mastoid, suggesting a restriction of secretory cells to the middle ear proper. It appears that obstruction of the aditus ad antrum contributes to the pathogenesis and accentuates pathologic conditions in otitis media.

Granulation Tissue↗

PubMed1988

Permeability of the human round-window membrane to cationic ferritin.

An ultrastructural study was done in three sequential steps to determine if the human round-window membrane was permeable to macromolecules. Cationic ferritin was first placed for one hour in the round-window niche of two live rhesus monkeys. The same tracer was then placed in the same manner in two rhesus monkeys that had been dead for one hour. In both groups, cationic ferritin was observed to traverse the round-window membrane through pinocytotic vesicles into the scala tympani. After establishing that the transport capabilities of the round-window membrane of the monkey remained present one hour after death, cationic ferritin was placed for one hour in the round-window niche of two humans who had been dead for 30 minutes and one hour. The tracer was observed to traverse the round-window membrane through pinocytotic vesicles into the scala tympani in both humans. This report may be the first to document morphologically the permeability of human round-window membranes to macromolecules.

Animals↗

PubMed1988

Experimental studies on round window structure: function and permeability.

Current research and an overall review of 12 years of round window membrane studies is presented. The approach, rationale, and concepts that have evolved from the studies are described. An ultrastructural study of the round window membrane of rhesus monkeys disclosed three basic layers: an outer epithelium, a middle core of connective tissue, and an inner epithelium. Morphologic evidence in monkeys, cats, and chinchillas suggests that these layers of the round window participate in absorption and secretion of substances to and from the inner ear, and that the entire membrane could play a role in the defense system of the ear. Cationic ferritin, horseradish peroxidase, 1-micron latex spheres, and neomycin-gold spheres placed in the middle ear of these experimental animals were observed to traverse the round window membrane through pinocytotic vesicles. Three-micron latex spheres and anionic ferritin were not incorporated by the membrane. Cationic ferritin and 1-micron latex spheres placed in perilymph were incorporated by the inner epithelial cells, suggesting absorptive capabilities of the round window membrane. Cationic ferritin was observed within the mesothelial cells underlying the scala tympani side of the basilar membrane, suggesting a role for these cells in the inner-ear defense system. A review of the subject and a general perspective from the author's viewpoint are discussed.

Animals↗

PubMed1983

Myofibroblasts in chronic otitis media.

Cells which may be tentatively described as myofibroblasts have been identified by transmission electron microscopy from samples of inflammatory tissue present in the tympanic cavity of ears demonstrating clinical chronic otitis media. These cells possess the ultrastructural characteristics of a markedly indented nucleus, well organized bundles of cytoplasmic microfilaments, and plasmalemma specializations resembling desmosomes. Myofibroblasts are contractile cells which are present in a number of pathological conditions characterized by tissue contraction or distortion such as hepatic cirrhosis, Dupuytren's contracture, and hypertrophic scars. It is possible to hypothesize that myofibroblasts in chronic otitis media may exert synchronized contractile forces which distort the tympanic membrane or ossicular chain and thus lead to conductive hearing loss.

Chronic Disease↗

PubMed1981

Passage of albumin from the middle ear to the inner ear in otitis media in the chinchilla.

A study of the permeability of the middle ear-inner ear interface for macromolecules was carried out in chinchillas with open and obstructed eustachian tubes utilizing tritiated human serum albumin and immunoelectrophoresis. Tritiated albumin was placed in the round window niche area or normal animals and animals in which the eustachian tubes had been obstructed for 24 hours or 14 days. The tritiated albumin was allowed to remain in the middle ear cavity for 24 hours, Samples of middle ear effusion, perilymph, blood and cerebrospinal fluid were collected and measured for radioactivity. Radioactivity was demonstrated in the perilymph. Samples of middle ear effusions and perilymph were also studied by immunoelectrophoresis with goat antihuman albumin. Albumin placed in the round window niche of an experimental animal could be recovered unchanged in the perilymph. The results suggest a pathophysiologic explanation for the association of otitis media and sensorineural hearing loss or endolymphatic hydrops.

Animals↗

PubMedDate not supplied

Normal and metastatic melanin in the temporal bone.

PURPOSE: Malignant melanoma is known to metastasize to the temporal bone. However, melanocytes exist in the normal inner ear and may be difficult to distinguish from metastatic melanotic cells. This study describes distribution of normal melanin in the ear and metastatic melanoma to the temporal bone. MATERIALS AND METHODS: Normal melanin distribution is described in 48 temporal bones from White (18), Native-American (19), and African-American (11) individuals and metastatic melanoma to the temporal bone is described in four cases (seven temporal bones). Temporal bones were removed at autopsy, fixed in 10% buffered formalin, and processed for routine celloidin embedding. Sections were cut at a thickness of 20 microns and every tenth section was stained with hematoxylin-eosin for light microscopic evaluation. RESULTS: Normal melanin was found in the inner ear, mainly around terminal neural structures and blood vessels, and occurred in greater quantities in African-American individuals. Metastatic melanotic cells reached the temporal bone by hematological dissemination, and by neural invasion from the central nervous system. No correlation was found between histopathological findings and clinical symptoms of patients. CONCLUSIONS: Metastatic melanoma to the temporal bone may be seen in the same areas as normal melanin. They may also be observed in bone marrow cells of the petrous bone and along the course of nerves of the internal auditory canal and cochlear vestibular labyrinth, either by following neural sheaths or blood vessels that run along the nerve. Metastatic disease to the temporal bone is often asymptomatic, or it may present with uncharacteristic symptoms that may delay diagnosis.

Adult↗